Helical piles have become a common piling system in the North American construction market. They are used for many applications with low to moderate tension and compression loads. Slender helical piles, less than 4.5 inches in diameter, have historically been used for light shear loads of 1 to 5 kips in vertical applications. This method derives the lateral capacity as a function of the pile’s allowable structural bending moment and the allowable passive earth pressure of the soil. It is common to analyze the capacity of the piles by theoretical slender pile equations, P-Y curves, or software programs that model P-Y response. An adequate safety factor or a service limit on the allowable deflection is applied to the allowable loads to determine an applicable pipe size. In recent years larger piles, with diameter greater than 5.5 inches, have been used for larger lateral loads. Large diameter piles have been designed for loads in excess of 20 kips.